import java.util.Scanner;

public class Main1610 {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        double x= sc.nextDouble();
        double y= sc.nextDouble();
        double z= sc.nextDouble();
        double a=x*8.5+y*5.6+z*6.2;
        System.out.println(String.format("%.1f",a));
    }
}
